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LM239: Use as pure charge counter without using VC1

Franz Schellhase
Expert 3605 points
Part Number: LM239


Hi Team,

A customer would like to use this device to do charge counting on a pre-fab 2S Li-Ion pack with integrated protection nd balancing. This means they cannot connect the node between the 2 cells. Is this possible?

Thank you,

Franz

  • +1
    TI__Guru 63786 points

    Hello Franz,

    Can you show an example of what your are trying to do? Either an actual existing schematic or block diagram?

    The LM239 is a comparator, not an amplifier - it will only provide a 1-bit output (when the voltage crosses a threshold). Charge counting usually involves measuring the cell voltage (analog) and current (analog) over time - not sure how you would do that with a comparator.

    The comparator  inputs are not "isolated", as in a ISO-type amplifer - the comparator inputs share a common GND pin and the input voltages must be contained between the GND pin potential and up to 2V below the comparator V+ pin.

    Accurately measuring a cell floating on top of another cell gets complicated as a ground referenced scheme, in that each cell shifts the reference points depending on charge.

    I am just not clear on your application.

  • 0 in reply to Paul Grohe
    TI__Expert 3605 points

    Hi Paul,

    Sorry for the confusion. Something went wrong in the device association. My question is related to BQ28Z610. I asked the question in the right forum again.

    Best regards,

    Franz